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| Titel |
Nitrogen assimilation and short term retention in a nutrient-rich tidal freshwater marsh – a whole ecosystem 15N enrichment study |
| VerfasserIn |
B. Gribsholt, E. Struyf, A. Tramper, L. Brabandere, N. Brion, S. Damme, P. Meire, F. Dehairs, J. J. Middelburg, H. T. S. Boschker |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 4, no. 1 ; Nr. 4, no. 1 (2007-01-11), S.11-26 |
| Datensatznummer |
250001495
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| Publikation (Nr.) |
 copernicus.org/bg-4-11-2007.pdf |
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| Zusammenfassung |
An intact tidal freshwater marsh system (3477 m2) was labelled by
adding 15N-ammonium as a tracer to the flood water inundating the
ecosystem. The appearance and retention of 15N-label in different marsh
components (leaves, roots, sediment, leaf litter and invertebrate fauna) was
followed over 15 days. This allowed us to elucidate the direct assimilation
and dependence on creek-water nitrogen on a relatively short term and
provided an unbiased assessment of the relative importance of the various
compartments within the ecosystem. Two separate experiments were conducted,
one in spring/early summer (May 2002) when plants were young and building up
biomass; the other in late summer (September 2003) when macrophytes were in
a flowering or early senescent state.
Nitrogen assimilation rate (per hour inundated) was >3 times faster in May
compared to September. On both occasions, however, the results clearly
revealed that the less conspicuous compartments such as leaf litter and
ruderal vegetations are more important in nitrogen uptake and retention than
the prominent reed (Phragmites australis) meadows. Moreover, short-term nitrogen retention in
these nutrient rich marshes occurs mainly via microbial pathways associated
with the litter and sediment. Rather than direct uptake by macrophytes, it
is the large reactive surface area provided by the tidal freshwater marsh
vegetation that is most crucial for nitrogen transformation, assimilation
and short term retention in nutrient rich tidal freshwater marshes. Our
results clearly revealed the dominant role of microbes in initial nitrogen
retention in marsh ecosystems. |
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